clear
Clears the current conversation history from the session.
This removes all messages from the active conversation. The chat session remains active and new messages can continue to be sent and received.
Note: This operation may fail in which case an error is delivered via ChatEventListener.onError:
NRError.ClearConversationDisabledError: Clear-conversation is disabled in the deployment configuration.
NRError.ClearConversationError: Feature is enabled, but clearing the conversation failed.